Valid Thursday January 19, 2017 to Monday January 30, 2017
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EST January 16 2017Synopsis
: An area of upper-level pressure and
enhanced onshore flow is likely to persist across the western U.S. during the
next week, while multiple low pressure systems advance across the central and
eastern U.S. During Week-2, a pattern change is expected with an area of
upper-level high pressure developing near the West Coast. Arctic high pressure
is forecast to remain centered over mainland Alaska through the weekend, while
a strong surface low is expected to enter the Bering Sea by early next week.
Detailed Summary For Thursday January 19 - Monday January 23:
- Periods of heavy precipitation (rain and
high-elevation snow) for parts of the western U.S., Thu-Mon, Jan 19-23.
- Periods of high winds for parts of western U.S. and southern high Plains,
Thu-Mon, Jan 19-23.
- Severe weather for parts of the Southeast, Sat, Jan 21.
- Periods of heavy rain for parts of the southeastern U.S., Thu-Sun, Jan
- Much below-normal temperatures for parts of mainland Alaska, Thu-Sun, Jan
- High winds for the Aleutians and Alaska Peninsula on Mon, Jan 23.
- Heavy precipitation (rain and high-elevation snow) for southeast mainland
Alaska and the Alaska Panhandle, Tue-Mon, Jan 24-30.
- High winds for southeast mainland Alaska and the Alaska Panhandle, Tue-Mon,
- A slight risk of much below-normal temperatures for parts of the interior
West, Tue-Thu, Jan 24-26.
- Flooding likely across parts of Washington.
- Flooding occurring along the middle Mississippi River.
- Severe Drought across parts of the eastern and southern U.S., Great Plains,
Arizona, California, and Colorado.
A series of
upper-level troughs, strong onshore flow, and enhanced Pacific moisture are
likely to result in periods of heavy precipitation (rain and high-elevation
snow) across southwest Oregon, California, southwest Utah, and Arizona during
this period. Deterministic model solutions indicate that the heaviest
precipitation (5 to 10 inches, liquid equivalent) is likely across the
orographically favored coastal ranges and Sierra Mountains of California. Snow
levels are generally expected to lower by early next week across the western
U.S. as 500-hpa heights decrease with snow levels potentially below 5,000 feet
across Arizona on Jan 23. Period of high winds (gusts above 50 mph) are also
forecast across from the western U.S east to the southern high Plains during
Although the shortwave troughs, emerging from the western U.S., are
expected to dampen as they progress into mean ridging aloft over the eastern
U.S., there is a signal for heavy rain across the southeastern U.S. due to
abundant low-level moisture for January. Therefore, periods of heavy rain are
forecast from the Gulf Coast north to the Tennessee Valley and southern
Appalachians from January 19 to 22. Model guidance indicates that 96-hour total
rainfall amounts could locally exceed 5 inches across the outlined area for
On January 21, the exit region of a strong mid-level jet, coinciding with
moderate instability and high low-level moisture, is expected to support severe
thunderstorms across parts of the southeastern U.S. The severe weather hazard
area for the southeastern U.S. is expected to be extended through Jan 22 in
subsequent outlooks. The unusual aspect of the storminess across the central
and eastern U.S. will be the lack of winter weather associated with the low
pressure systems, given the absence of cold air.
Much below-normal temperatures are posted for mainland Alaska through Jan
22, where the 6z GFS ensemble mean indicates temperatures averaging more than
20 degrees F below normal. The deterministic models indicate that a potent low
pressure system (around 964-hpa) will enter the Bering Sea and bring high winds
(50 knots or greater) to the Aleutians and Alaska Peninsula on Jan
For Tuesday January 24 - Monday January 30:
The ensemble means are in good
agreement and remain consistent that a major pattern change occurs during the
final week of January. An upper-level ridge is expected to build near the West
Coast, resulting in a much drier pattern for the Pacific Northwest and northern
California. Meanwhile, a full latitude trough is forecast to extend from Hudson
Bay to the central U.S. This longwave pattern is expected to favor a trend
towards more seasonal temperatures across the central and eventually the
eastern U.S. later in Week-2.
Surface high pressure is expected to become centered over the Great Basin
early in the Week-2 period. A slight risk of much below-normal temperatures is
posted for parts of the interior West where strong low-level inversions are
An upper-level trough, located south of the Aleutians, favors multiple low
pressure systems with onshore flow affecting southeast Alaska and the Alaska
Panhandle during Week-2. Heavy precipitation (rain and high-elevation snow with
amounts of more than 1.5 inches per 24 hours) and high winds (speeds greater
than 50 knots) are posted for these areas throughout the period.
According to the latest U.S. Drought Monitor (USDM) valid on January 10,
the coverage of severe or greater drought for the CONUS decreased from 8.63 to
7.96%. One to two category improvements were made to the drought areas across
parts of California and Nevada from the previous week.
Click here to see a display of the GFS Ensemble Forecasts
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.